Mechanics

MISFIRE AND LOW FUEL PRESSURE

2001 Chevrolet Blazer • 4.3L 6 cylinder 4WD Automatic • 90,000 miles

Hey guys I have a 01 blazer with 4.3 v6 in it 2 door. The vehicle was running rough so I did a tune up to it, spark plugs cap rotor and wire. I get a p300 random misfire code and the car start hard. I put a fuel pressure gauge on it and when cranking and starting I am only getting 55-58 psi fuel pressure and then when the car shuts off within 30 seconds it drops to zero. It doesnt immediately drop to zero but over 30 seconds slowly drops which I know isnt good and causing my hard starting. My misfire and rough idle could maybe be from not enough fuel pressure? Since this car has all metal and hard plastic return lines I cant easily close the return to check to see if the pressure increases. Could the spider injector cause this. Having trouble trying to figure if its the pump, fuel pressure regulator or spider injector. I dont have a gas smell in the oil. Any help would be greatly appreciated. Thanks
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J02ws6transam
May 31, 2014.




Fuel pressure should be 60-66 psi and hold for 5 minutes with in 10 psi. Sounds like a pump but if misfire code does not go away have a pro diagnose it as these are extremely hard to find.
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Hmac300
May 31, 2014.
Ok thank you for the fast response. I will try the pump first.

Tiny
J02ws6transam
May 31, 2014.

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